The present invention, in some embodiments thereof, relates to a global location register for LTE/4G, and, more particularly, but not exclusively, to a way of using the global location register in a network that requires 3G for voice calls, the global location register being expected to mobile handset manage the passage of the mobile handset between 4G and 3G without notifying the home network.
The GLR (Global Location Register) has been standardized by 3GPP/ETSI for the GSM/3G network. The GLR is a core network component, connected between the VLRs and the HLR and typically located in the mobile network. The GLR receives the Update Location registration attempts from the VLRs, but does not necessarily relay these signals to the HLR at the home network. Instead, the GLR records the real VLR address, and sends a confirmation to the VLR as if it is the HLR. The HLR remains unaware that this registration has taken place at all, since the HLR assumes the subscriber is registered in the GLR. This is because, at the initial roaming registration the GLR provided its address to the HLR as the serving VLR. From now on, the GLR does not have to provide additional updates to the HLR. The GLR in the 3G world continues to emulate the VLR to the HLR, and in the other direction emulates the HLR to the VLR.
The GLR component was designed in order to save signaling traffic between the VLRs and the HLR, and is found useful in roaming scenarios, where the VLRs are in the roaming network and the HLR in the home network. In that case, the international signaling traffic may be reduced dramatically. The GLR is also used for anti-steering of roaming, preventing the home network from steering away the subscriber from the visited network to other networks that the home network may prefer. Steering is possible whenever a registration attempt reaches the home network. Minimizing these events may minimize opportunities for steering of roaming away from the current visited network by the home network.
The GLR has not been standardized for LTE/4G networks, which differ from the 3G networks in that they use the Diameter protocol, in place of the MAP used by 2G/3G case. Furthermore, attempting to use a GLR in the 4G environment runs up against a problem.
Voice communication in 4G is supposed to use Voice over IP (VoIP) for actual mobile handset calls but many 4G networks retain the standard circuit switching methodology used by 3G and 2G for voice calls, and thus when voice calls are required, a protocol called circuit switch fall back (CSFB) is used and the mobile handset temporarily re-registers as a 3G mobile handset for the duration of the call, and subsequently returns to the 4G registration. But the 3G and 4G registrations are mutually incompatible and use different infrastructure, and the location registers find that they do not have the necessary information for changing between the 3G and 4G protocols and infrastructure without involving the home network. Thus the GLR is unable to perform its task.